Some “small groups’ of the Taliban have expressed willingness in talking with the Afghan government to end the nearly 17-year-old war in Afghanistan, the U.S. Defense Secretary Jim Mattis said on Tuesday during an unannounced visit to Kabul.

“We’ve had some groups of Taliban – small groups – who have either started to come over or expressed an interest in talking,” Mattis said.

“In other words, it may not be that the whole Taliban comes over in one fell swoop. That may be a bridge too far to expect. But there are elements of the Taliban clearly interested in talking to the Afghan government,” he said.

Mattis added that the U.S. wants the Afghan government to lead and to provide “the substance” to the reconciliation efforts.

Meeting with Mattis in Gul Khana Palace, President Ashraf Ghani described the new U.S. strategy as a game changer. “It has been a game changer because it has forced every actor to re-examine their assumptions,” Ghani said.

This comes as the Afghan government offered unconditional talks with the Taliban insurgent group, last month, in what was seen by the U.S. officials as a major step toward reconciliation effort from Kabul.